Liquid crystal display with uniform feed-through voltage

ABSTRACT

A liquid crystal display with uniform feed-through voltage includes a plurality of data lines for receiving a plurality of data signals respectively, a plurality of gate lines for receiving a plurality of gate signals respectively, a plurality of common lines for receiving a common voltage, a plurality of storage units, a plurality of first switches, and a plurality of second switches. Each storage unit includes a first liquid crystal capacitor and a second liquid crystal capacitor coupled to a corresponding common line. Each first switch is coupled to a corresponding data line, a corresponding gate line, and a corresponding first liquid crystal capacitor. Each second switch is coupled to a corresponding gate line, a corresponding first switch, and a corresponding second liquid crystal capacitor. The capacitance of the gate-source capacitor of each first switch is greater than the capacitance of the gate-source capacitor of each second switch.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display, and moreparticularly, to a liquid crystal display with uniform feed-throughvoltage.

2. Description of the Prior Art

Because liquid crystal displays (LCDs) are characterized by thinappearance, low power consumption, and low radiation, LCDs have beenwidely applied in various electronic products such as computer monitors,mobile phones, personal digital assistants (PDAs), or flat paneltelevisions. In general, the LCD comprises a liquid crystal layerencapsulated by two substrates. The operation of an LCD is featured byvarying voltage drops between opposite sides of different sections ofthe liquid crystal layer for twisting the angles of the liquid crystalmolecules in different sections of the liquid crystal layer so that thetransparency of different sections of the liquid crystal layer can becontrolled accordingly for illustrating images.

It is well known that each pixel of an LCD can be designed to comprisetwo sub-pixels for achieving a wide viewing angle. That is, based ongray level averaging effect of two Gamma curves corresponding to the twosub-pixels, optimal visual experience can be realized in differentviewing angles for having a high-quality wide viewing angle. However, inthe data signal driving operation of the liquid crystal display, theevent of different feed-through voltages will occur to the chargingoperation concerning the two sub-pixels. Accordingly, the phenomena offlickering and color-shift arise on the screen of the liquid crystaldisplay. In order to solve the flickering and color-shift phenomena, twodifferent common lines can be utilized to compensate differentfeed-through voltages occurring to the voltage drops of the liquidcrystal capacitors of the two sub-pixels. Nevertheless, the prior-arttechnique for solving the flickering and color-shift phenomena is paidby the complicated design of driving modules and control circuits of theliquid crystal display, which in turn will significantly increaseproduction cost. Furthermore, the event of different feed-throughvoltages will also reduce the available voltage range of each pixel ofthe liquid crystal display, and the available contrast range forbrightness control of each pixel of the liquid crystal display isreduced accordingly.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, a liquidcrystal display with uniform feed-through voltage is disclosed. Theliquid crystal display comprises a plurality of data lines, a pluralityof gate lines, a plurality of common lines, a plurality of storageunits, a plurality of first switches, and a plurality of secondswitches.

Each of the data lines is utilized to receive a corresponding datasignal. The gate lines are crossed with the plurality of data linesperpendicularly. Each of the plurality of gate lines is utilized toreceive a corresponding gate signal. The common lines are utilized toreceive a common voltage. Each of the plurality of storage unitscomprises a first liquid crystal capacitor and a second liquid crystalcapacitor. The first liquid crystal capacitor comprises a first end anda second end. The first end of the first liquid crystal capacitor iscoupled to a corresponding common line of the plurality of common lines.The second liquid crystal capacitor comprises a first end and a secondend. The first end of the second liquid crystal capacitor is coupled tothe corresponding common line of the plurality of common lines. Each ofthe plurality of first switches comprises a first end, a second end, agate, and a first end capacitor. The first end of the first switch iscoupled to the second end of a corresponding first liquid crystalcapacitor of the plurality of first liquid crystal capacitors. Thesecond end of the first switch is coupled to a corresponding data lineof the plurality of data lines. The gate of the first switch is coupledto a corresponding gate line of the plurality of gate lines. The signalconnection between the first end and the second end of the first switchis controlled based on a gate signal furnished to the gate of the firstswitch via the corresponding gate line. The first end capacitor of thefirst switch is coupled between the gate and the first end of the firstswitch. Each of the plurality of second switches comprises a first end,a second end, a gate, and a first end capacitor. The first end of thesecond switch is coupled to the second end of a corresponding secondliquid crystal capacitor of the plurality of second liquid crystalcapacitors. The second end of the second switch is coupled to the firstend of a corresponding first switch of the plurality of first switches.The gate of the second switch is coupled to a corresponding gate line ofthe plurality of gate lines. The signal connection between the first endand the second end of the second switch is controlled based on a gatesignal furnished to the gate of the second switch via the correspondinggate line. The first end capacitor of the second switch is coupledbetween the gate and the first end of the second switch. The capacitanceof the first end capacitor of the first switch is greater than thecapacitance of the first end capacitor of the second switch.

In accordance with another embodiment of the present invention, a liquidcrystal display with uniform feed-through voltage is disclosed. Theliquid crystal display comprises a plurality of data lines, a pluralityof gate lines, a plurality of first common lines, a plurality of secondcommon lines, a plurality of storage units, a plurality of firstswitches, and a plurality of second switches.

Each of the plurality of data lines is utilized to receive acorresponding data signal. The plurality of gate lines are crossed withthe plurality of data lines perpendicularly. Each of the plurality ofgate lines is utilized to receive a corresponding gate signal. The firstcommon lines are utilized to receive a first common voltage. The secondcommon lines are utilized to receive a second common voltage. Each ofthe plurality of storage units comprises a first liquid crystalcapacitor and a second liquid crystal capacitor. The first liquidcrystal capacitor comprises a first end and a second end. The first endof the first liquid crystal capacitor is coupled to a correspondingfirst common line of the plurality of first common lines. The secondliquid crystal capacitor comprises a first end and a second end. Thefirst end of the second liquid crystal capacitor is coupled to thecorresponding second common line of the plurality of second commonlines. Each of the plurality of first switches comprises a first end, asecond end, a gate, and a first end capacitor. The first end of thefirst switch is coupled to the second end of a corresponding firstliquid crystal capacitor of the plurality of first liquid crystalcapacitors. The second end of the first switch is coupled to acorresponding data line of the plurality of data lines. The gate of thefirst switch is coupled to a corresponding gate line of the plurality ofgate lines. The signal connection between the first end and the secondend of the first switch is controlled based on a gate signal furnishedto the gate of the first switch via the corresponding gate line. Thefirst end capacitor of the first switch is coupled between the gate andthe first end of the first switch. Each of the plurality of secondswitches comprises a first end, a second end, a gate, and a first endcapacitor. The first end of the second switch is coupled to the secondend of a corresponding second liquid crystal capacitor of the pluralityof second liquid crystal capacitors. The second end of the second switchis coupled to the first end of a corresponding first switch of theplurality of first switches. The gate of the second switch is coupled toa corresponding gate line of the plurality of gate lines. The signalconnection between the first end and the second end of the second switchis controlled based on a gate signal furnished to the gate of the secondswitch via the corresponding gate line. The first end capacitor of thesecond switch is coupled between the gate and the first end of thesecond switch. The capacitance of the first end capacitor of the firstswitch is greater than the capacitance of the first end capacitor of thesecond switch.

In accordance with another embodiment of the present invention, a liquidcrystal display with uniform feed-through voltage is disclosed. Theliquid crystal display comprises a plurality of data lines, a pluralityof gate lines, a plurality of common lines, a plurality of storageunits, a plurality of first switches, and a plurality of secondswitches.

Each of the plurality of data lines is utilized to receive acorresponding data signal. The plurality of gate lines are crossed withthe plurality of data lines perpendicularly. Each of the plurality ofgate lines is utilized to receive a corresponding gate signal. Thecommon lines are utilized to receive a common voltage. Each of theplurality of storage units comprises a first liquid crystal capacitorand a second liquid crystal capacitor. The first liquid crystalcapacitor comprises a first end and a second end. The first end of thefirst liquid crystal capacitor is coupled to a corresponding common lineof the plurality of common lines. The second liquid crystal capacitorcomprises a first end and a second end. The first end of the secondliquid crystal capacitor is coupled to the corresponding common line ofthe plurality of common lines. Each of the plurality of first switchescomprises a first end, a second end, a gate channel, and a gate. Thefirst end of the first switch is coupled to the second end of acorresponding first liquid crystal capacitor of the plurality of firstliquid crystal capacitors. The second end of the first switch is coupledto a corresponding data line of the plurality of data lines. The gatechannel of the first switch is coupled between the first end and thesecond end of the first transistor. The gate of the first switch iscoupled to a corresponding gate line of the plurality of gate lines. Thesignal connection between the first end and the second end of the firstswitch is controlled based on a gate signal furnished to the gate of thefirst switch via the corresponding gate line. Each of the plurality ofsecond switches comprises a first end, a second end, a gate, and a firstend capacitor. The first end of the second switch is coupled to thesecond end of a corresponding second liquid crystal capacitor of theplurality of second liquid crystal capacitors. The second end of thesecond switch is coupled to the first end of a corresponding firstswitch of the plurality of first switches. The gate channel of thesecond switch is coupled between the first end and the second end of thesecond transistor. The gate of the second switch is coupled to acorresponding gate line of the plurality of gate lines. The signalconnection between the first end and the second end of the second switchis controlled based on a gate signal furnished to the gate of the secondswitch via the corresponding gate line. The ratio of width to length ofthe gate channel of the first switch is greater than the ratio of widthto length of the gate channel of the second switch.

In accordance with another embodiment of the present invention, a liquidcrystal display with uniform feed-through voltage is disclosed. Theliquid crystal display comprises a plurality of data lines, a pluralityof gate lines, a plurality of first common lines, a plurality of secondcommon lines, a plurality of storage units, a plurality of firstswitches, and a plurality of second switches.

Each of the plurality of data lines is utilized to receive acorresponding data signal. The plurality of gate lines are crossed withthe plurality of data lines perpendicularly. Each of the plurality ofgate lines is utilized to receive a corresponding gate signal. The firstcommon lines are utilized to receive a first common voltage. The secondcommon lines are utilized to receive a second common voltage. Each ofthe plurality of storage units comprises a first liquid crystalcapacitor and a second liquid crystal capacitor. The first liquidcrystal capacitor comprises a first end and a second end. The first endof the first liquid crystal capacitor is coupled to a correspondingcommon line of the plurality of common lines. The second liquid crystalcapacitor comprises a first end and a second end. The first end of thesecond liquid crystal capacitor is coupled to the corresponding commonline of the plurality of common lines. Each of the plurality of firstswitches comprises a first end, a second end, a gate channel, and agate. The first end of the first switch is coupled to the second end ofa corresponding first liquid crystal capacitor of the plurality of firstliquid crystal capacitors. The second end of the first switch is coupledto a corresponding data line of the plurality of data lines. The gatechannel of the first switch is coupled between the first end and thesecond end of the first transistor. The gate of the first switch iscoupled to a corresponding gate line of the plurality of gate lines. Thesignal connection between the first end and the second end of the firstswitch is controlled based on a gate signal furnished to the gate of thefirst switch via the corresponding gate line. Each of the plurality ofsecond switches comprises a first end, a second end, a gate, and a firstend capacitor. The first end of the second switch is coupled to thesecond end of a corresponding second liquid crystal capacitor of theplurality of second liquid crystal capacitors. The second end of thesecond switch is coupled to the first end of a corresponding firstswitch of the plurality of first switches. The gate channel of thesecond switch is coupled between the first end and the second end of thesecond transistor. The gate of the second switch is coupled to acorresponding gate line of the plurality of gate lines. The signalconnection between the first end and the second end of the second switchis controlled based on a gate signal furnished to the gate of the secondswitch via the corresponding gate line. The ratio of width to length ofthe gate channel of the first switch is greater than the ratio of widthto length of the gate channel of the second switch.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram schematically showing the structure of aliquid crystal display (only circuits related to charging/dischargingcontrol operation for sub-pixels are shown) in accordance with a firstembodiment of the present invention.

FIG. 2 shows the related signal waveforms concerning the operation ofthe liquid crystal display in FIG. 1, having time along the abscissa.

FIG. 3 is a diagram schematically showing a layout of the first switchshown in FIG. 1.

FIG. 4 is a circuit diagram schematically showing the structure of aliquid crystal display in accordance with a second embodiment of thepresent invention.

FIG. 5 shows the related signal waveforms concerning the operation ofthe liquid crystal display in FIG. 4, having time along the abscissa.

FIG. 6 is a circuit diagram schematically showing the structure of aliquid crystal display in accordance with a third embodiment of thepresent invention.

FIG. 7 is a circuit diagram schematically showing the structure of aliquid crystal display in accordance with a fourth embodiment of thepresent invention.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Here,it is to be noted that the present invention is not limited thereto.

FIG. 1 is a circuit diagram schematically showing the structure of aliquid crystal display 100 (only circuits related to charging controloperation for sub-pixels are shown) in accordance with a firstembodiment of the present invention. As shown in FIG. 1, the liquidcrystal display 100 comprises a plurality of parallel data lines 110, aplurality of parallel gate lines 120, a plurality of parallel commonlines 130, a plurality of storage units 140, a plurality of firstswitches 150, and a plurality of second switches 160. Each pixel area ofthe liquid crystal display 100 is sectioned by adjacent data lines 110and adjacent gate lines 120. Each pixel area comprises a correspondingstorage unit 140, a corresponding first switch 150, and a correspondingsecond switch 160.

The data lines 110 are utilized to receive corresponding data signalsV_(D1)-V_(Dm) respectively. The plurality of gate lines 120 are crossedwith the plurality of data lines 110 perpendicularly and are utilized toreceive corresponding gate signals V_(G1)-V_(Gn) respectively. Thecommon lines 130 are parallel to the plurality of gate lines 120. Eachof the plurality of common lines 130 is utilized to receive a commonvoltage Vcom. Each storage unit 140 is corresponding to a pixel. Eachpixel comprises a first sub-pixel and a second sub-pixel. The firstsub-pixel comprises a first liquid crystal capacitor 143 having a firstcapacitance C_(B), which is also termed as a bright capacitance. Thesecond sub-pixel comprises a second liquid crystal capacitor 145 havinga second capacitance C_(D), which is also termed as a dark capacitance.Each first liquid crystal capacitor 143 comprises a first end and asecond end. The first end of the first liquid crystal capacitor 143 iscoupled to a corresponding common line 130. Each second liquid crystalcapacitor 145 comprises a first end and a second end. The first end ofthe second liquid crystal capacitor 145 is coupled to a correspondingcommon line 130.

Each first switch 150 comprises a first end, a second end, a gate, afirst end capacitor 153, and a gate channel. The first end of a firstswitch 150 is coupled to the second end of a corresponding first liquidcrystal capacitor 143. The second end of a first switch 150 is coupledto a corresponding data line 110. The gate of a first switch 150 iscoupled to a corresponding gate line 120. The first end capacitor 153 ofa first switch 150 is coupled between the gate and the first end of thefirst switch 150. The gate channel of a first switch 150 is coupledbetween the first end and the second end of the first switch 150. Eachfirst switch 150 controls a signal connection between the first end andthe second end of the first switch 150 based on a gate signal furnishedto the gate of the first switch 150 via the corresponding gate line 120.The first switches 150 comprise thin film transistors or metal oxidesemiconductor (MOS) field effect transistors. That is, for example, thefirst end of a first switch 150 can be a source, the second end of thefirst switch 150 can be a drain, and the first end capacitor 153 of thefirst switch 150 can be a gate-source capacitor having a capacitanceCgs1. The gate channel of a first switch 150 has a width measured alonga direction perpendicular to the drain-source current flowing directionof the first switch 150. Furthermore, the gate channel of a first switch150 has a length measured along a direction parallel to the drain-sourcecurrent flowing direction of the first switch 150.

Each second switch 160 comprises a first end, a second end, a gate, afirst end capacitor 163, and a gate channel. The first end of a secondswitch 160 is coupled to the second end of a corresponding second liquidcrystal capacitor 145. The second end of a second switch 160 is coupledto the first end of the first transistor 150 of an adjacent pixel area.The gate of a second switch 160 is coupled to a corresponding gate line120. The first end capacitor 163 of a second switch 160 is coupledbetween the gate and the first end of the second switch 160. The gatechannel of a second switch 160 is coupled between the first end and thesecond end of the second switch 160. Each second switch 160 controls asignal connection between the first end and the second end of the secondswitch 160 based on a gate signal furnished to the gate of the secondswitch 160 via the corresponding gate line 120. The second switches 160comprise thin film transistors or MOS field effect transistors. That is,the first end of a second switch 160 can be a source, the second end ofthe second switch 160 can be a drain, and the first end capacitor 163 ofthe second switch 160 can be a gate-source capacitor having acapacitance Cgs2. The gate channel of a second switch 160 has a widthmeasured along a direction perpendicular to the drain-source currentflowing direction of the second switch 160. Furthermore, the gatechannel of a second switch 160 has a length measured along a directionparallel to the drain-source current flowing direction of the secondswitch 160.

FIG. 2 shows the related signal waveforms concerning the operation ofthe liquid crystal display 100 in FIG. 1, having time along theabscissa. For the sake of elucidation, only the related signal waveformsfor the charging/discharging operation concerning a first pixel area 101and a second pixel area 102 of the liquid crystal display 100 based ontwo gate signals V_(G1), V_(G2) and one data signal V_(D1) are shown inFIG. 2. As shown in FIG. 1, the first switch 150 of the first pixel area101 is also labeled as a switch SW11, the second switch 160 of the firstpixel area 101 is also labeled as a switch SW12, the first switch 150 ofthe second pixel area 102 is also labeled as a switch SW21, and thesecond switch 160 of the second pixel area 102 is also labeled as aswitch SW22. The voltage at the second end of the first liquid crystalcapacitor 143 of the first pixel area 101 is labeled as a first voltageV1. The voltage at the second end of the second liquid crystal capacitor145 of the first pixel area 101 is labeled as a second voltage V2.

The signal waveforms in FIG. 2, from top to bottom, are the gate signalV_(G1), the gate signal V_(G2), the data signal V_(D1), the secondvoltage V2, and the first voltage V1. When the gate signal V_(G2) ischanging from a high voltage level to a low voltage level at time t1,the state of the switch SW21 is switched from an on-state to anoff-state. Since the gate signal V_(G1) retains a high voltage level attime t1, both the states of the switches SW11 and SW12 continueon-states. Accordingly, the second voltage V2 shifts down a feed-throughvoltage Vft21 shown in FIG. 2 due to turning off the switch SW21together with the level-shifting of the gate signal V_(G2). Thefeed-through voltage Vft21 can be expressed according to the Formula (1)listed below.

$\begin{matrix}{{{Vft}\; 21} = {\frac{{Cgs}\; 1}{C_{D} + C_{B} + {{Cgs}\; 1}}\Delta\; V_{G\; 2}}} & {{Formula}\mspace{20mu}(1)}\end{matrix}$

In Formula (1), Cgs1 represents the capacitance of the first endcapacitor 153 of the switch SW21, C_(D) represents the capacitance ofthe second liquid crystal capacitor 145 of the first pixel area 101,C_(B) represents the capacitance of the first liquid crystal capacitor143 of the second pixel area 102, and ΔV_(G2) represents the voltagedifference between the high voltage level and the low voltage level ofthe gate signal V_(G2).

When the gate signal V_(G1) is changing from a high voltage level to alow voltage level at time t2, both the states of the switches SW11 andSW12 are switched from on-states to off-states. Accordingly, the secondvoltage V2 shifts down a feed-through voltage Vft22 shown in FIG. 2 dueto turning off the switch SW12 together with the level-shifting of thegate signal V_(G1). Besides, the first voltage V1 shifts down afeed-through voltage Vft1 shown in FIG. 2 due to turning off the switchSW11 together with the level-shifting of the gate signal V_(G1). Thefeed-through voltages Vft22 and Vft1 can be expressed according to theFormulas (2) and (3) listed below.

$\begin{matrix}{{{Vft}\; 22} = {\frac{{Cgs}\; 2}{C_{D} + {{Cgs}\; 2}}\Delta\; V_{G\; 1}}} & {{Formula}\mspace{20mu}(2)} \\{{{Vft}\; 1} = {\frac{{Cgs}\; 1}{C_{B} + {C\;{gs}\; 1}}\Delta\mspace{11mu} V_{G\; 1}}} & {{Formula}\mspace{20mu}(3)}\end{matrix}$

In Formulas (2) and (3), Cgs2 represents the capacitance of the firstend capacitor 163 of the switch SW12, Cgs1 represents the capacitance ofthe first end capacitor 153 of the switch SW11, C_(D) represents thecapacitance of the second liquid crystal capacitor 145 of the firstpixel area 101, C_(B) represents the capacitance of the first liquidcrystal capacitor 143 of the first pixel area 101, and ΔV_(G1)represents the voltage difference between the high voltage level and thelow voltage level of the gate signal V_(G1).

Accordingly, based on the signal waveforms shown in FIG. 2, after thechanges of the gate signals V_(G2) and V_(G1) from the high voltagelevel to the low voltage level at times t1 and t2 respectively, thefirst voltage V1 of the first liquid crystal capacitor 143 of the firstpixel area 101 shifts down the feed-through voltage Vft1, and the secondvoltage V2 of the second liquid crystal capacitor 145 of the first pixelarea 101 shifts down a feed-through voltage Vft2. The feed-throughvoltage Vft2 is a sum of the feed-through voltage Vft21 and thefeed-through voltage Vft22. In the data signal driving operation of aprior-art liquid crystal display, the flickering and color-shiftphenomena will occur due to significant discrepancy between thefeed-through voltages Vft1 and Vft2. In general, the feed-throughvoltage Vft2 is greater than the feed-through voltage Vft1. Besides, thediscrepancy between the feed-through voltages Vft1 and Vft2 will alsoreduce available contrast range for brightness control of each pixel.

For that reason, in one preferred embodiment, the capacitance Cgs1 canbe adjusted according to the Formula (4) listed below so that thefeed-through voltages Vft1 and Vft2 are substantially equal foreliminating the color-shift phenomenon.

$\begin{matrix}{{\frac{{Cgs}\; 1}{C_{D} + C_{B} + {{Cgs}\; 1}} + \frac{{Cgs}\; 2}{C_{D} + {{Vgs}\; 2}}} = \frac{{Cgs}\; 1}{C_{B} + {{Cgs}\; 1}}} & {{Formula}\mspace{20mu}(4)}\end{matrix}$

The voltage differences ΔV_(G1) and ΔV_(G2) are not shown in Formula (4)because the voltage differences ΔV_(G1) and ΔV_(G2) are normally equaland thus can be taken out. That is, through adjusting the capacitanceCgs1 based on the capacitances C_(D), C_(B), and Cgs2 according toFormula (4), the feed-through voltage Vft1 can be set to equal thefeed-through voltage Vft2. In other words, through adjusting thecapacitance Cgs1 of the first end capacitor 153 of the first switch 150,the liquid crystal display having uniform feed-through voltage can beimplemented. In general, the adjusted capacitance Cgs1 is greater thanthe capacitance Cgs2. Furthermore, in order to diminish the flickeringphenomenon, the common voltage Vcom shown in FIG. 2 can be set to changein response to the feed-through voltage shift of the first voltage V1 orthe second voltage V2.

FIG. 3 is a diagram schematically showing a layout of the first switch150 shown in FIG. 1. As shown in FIG. 3, the capacitor area Ax of thefirst end capacitor 153 of the first switch 150 is indicated by asingle-hatched region. Therefore, the required capacitance Cgs1 of thefirst end capacitor 153 can be designed by sizing the capacitor area Ax.Besides, by adjusting the thickness or dielectric constant of theinsulation layer of the first end capacitor 153, the requiredcapacitance Cgs1 of the first end capacitor 153 can also be designed.

Based on the above description, the capacitance Cgs1 being adjustedshould be greater than the capacitance Cgs2. Accordingly, in oneembodiment, the capacitor area of the first end capacitor 153 of thefirst switch 150 can be adjusted to be greater than the capacitor areaof the first end capacitor 163 of the second switch 160 so that therequired capacitance Cgs1 of the first end capacitor 153 can beachieved. In another embodiment, the thickness of the insulation layerof the first end capacitor 153 of the first switch 150 can be adjustedto be thinner than the thickness of the insulation layer of the firstend capacitor 163 of the first switch 160 so that the requiredcapacitance Cgs1 of the first end capacitor 153 can be achieved. In theother embodiment, the dielectric constant of the insulation layer of thefirst end capacitor 153 of the first switch 150 can be adjusted to begreater than the dielectric constant of the insulation layer of thefirst end capacitor 163 of the first switch 160 so that the requiredcapacitance Cgs1 of the first end capacitor 153 can be achieved.Alternatively, the required capacitance Cgs1 of the first end capacitor153 can also be achieved by adjusting at least two parameters of thecapacitor area, the thickness and the dielectric constant of theinsulation layer of the first end capacitor 153.

It is well known that the capacitance ratio C_(D)/C_(B) of thecapacitance C_(D) of the second liquid crystal capacitor 145 to thecapacitance C_(B) of the first liquid crystal capacitor 143 affects theavailable viewing angle of the liquid crystal display 100. In general,the range of the available viewing angle can be wider as the capacitanceratio C_(D)/C_(B) is greater. However, as the capacitance ratioC_(D)/C_(B) is greater, the ratio of the charging period ΔT1 to thecharging period ΔT2, as shown in FIG. 2, is normally adjusted to begreater. In one embodiment, as the capacitance ratio C_(D)/C_(B) is setto be a ratio of 2 to 1, the ratio of the charging period ΔT1 to thecharging period ΔT2 is set to be a ratio of 3 to 1. However, as thecharging period ΔT2 shrinks, the color-shift phenomenon caused bydeficient color saturation will occur due to lower charging ratio of thefirst liquid crystal capacitor 143. In order to boost the charging ratioof the first liquid crystal capacitor 143, the ratio of the width W tothe length L of the gate channel of the first switch 150, as shown inFIG. 3, can be designed to have a higher value, and meanwhile, thecapacitance Cgs1 of the first end capacitor 153 can also be adjusted tohave the desirable value.

FIG. 4 is a circuit diagram schematically showing the structure of aliquid crystal display 400 in accordance with a second embodiment of thepresent invention. As shown in FIG. 4, the circuit structure of theliquid crystal display 400 is similar to the circuit structure of theliquid crystal display 100 shown in FIG. 1, differing only in that theplurality of parallel common lines 130 are replaced with a plurality ofparallel first common lines 131 and a plurality of parallel secondcommon lines 132. All the pluralities of first common lines 131 andsecond common lines 132 are parallel to the plurality of gate lines 120.Each of the plurality of first common lines 131 is utilized to receive afirst common voltage Vcom1, and each of the plurality of second commonlines 132 is utilized to receive a second common voltage Vcom2. Thefirst end of each first liquid crystal capacitor 143 is coupled to acorresponding first common line 131. The first end of each second liquidcrystal capacitor 145 is coupled to a corresponding second common line132. The other circuits of the liquid crystal display 400 are identicalto the circuits of the liquid crystal display 100, and for the sake ofbrevity, further discussion on the other circuits of liquid crystaldisplay 400 is omitted.

FIG. 5 shows the related signal waveforms concerning the operation ofthe liquid crystal display 400 in FIG. 4, having time along theabscissa. For the sake of elucidation, only the related signal waveformsfor the charging/discharging operation concerning a first pixel area 101and a second pixel area 102 of the liquid crystal display 400 based ontwo gate signals V_(G1), V_(G2) and one data signal V_(D1) are shown inFIG. 5. It is obvious that the signal waveforms of the gate signalV_(G1), the gate signal V_(G2), the data signal V_(D1), the secondvoltage V2, and the first voltage V1 shown in FIG. 5 are identical tothose shown in FIG. 2. Accordingly, the corresponding relationshipsconcerning the feed-through voltages Vft21, Vft22, and Vft1 can also beexpressed as the Formulas (1), (2), and (3). In one preferredembodiment, the capacitance Cgs1 can be also adjusted according to theFormula (4) so that the feed-through voltages Vft1 and Vft2 aresubstantially equal for eliminating the color-shift phenomenon. However,the common voltage Vcom in FIG. 2 is replaced with a first commonvoltage Vcom1 and a second common voltage Vcom2 in FIG. 5. Moreover, inorder to get rid of the flickering phenomenon, the first common voltageVcom1 shown in FIG. 5 is set to change in response to the feed-throughvoltage shift of the first voltage V1, and the second common voltageVcom2 shown in FIG. 5 is set to change in response to the feed-throughvoltage shift of the second voltage V2.

In summary, the liquid crystal display 400 is able to eliminate thecolor-shift phenomenon based on a design having required capacitanceCgs1. Furthermore, the liquid crystal display 400 is also able to getrid of the flickering phenomenon through providing the first commonvoltage Vcom1 and the second common voltage Vcom2 individually changingin response to the feed-through voltage shifts of the first voltage V1and the second voltage V2 respectively to each first common line 131 andeach second common line 132. Moreover, the circuit designed forproviding the first common voltage Vcom1 and the second common voltageVcom2 can be simplified due to identical feed-through voltages Vft1 andVft2. In addition, because of the uniform feed-through voltage in theoperation of the liquid crystal display 400, the reduction of availablecontrast range for brightness control of each pixel of the liquidcrystal display 400 is not as serious as that of the prior-art liquidcrystal display. Similarly, as the capacitance ratio C_(D)/C_(B) isincreased, the color-shift phenomenon caused by deficient colorsaturation due to reduction of the charging period ΔT2 can becompensated by devising the first switch 150 with the gate channelhaving a greater width/length ratio.

FIG. 6 is a circuit diagram schematically showing the structure of aliquid crystal display 600 in accordance with a third embodiment of thepresent invention. As shown in FIG. 6, the circuit structure of theliquid crystal display 600 is similar to the circuit structure of theliquid crystal display 100 shown in FIG. 1, differing only in that theplurality of parallel common lines 130 are replaced with a plurality ofparallel common lines 133. The common lines 133 are perpendicular to theplurality of gate lines 120. Each of the plurality of common lines 133receives a common voltage Vcom. The first ends of the first liquidcrystal capacitor 143 and the second liquid crystal capacitor 145 ofeach pixel are both coupled to a corresponding common line 133. Theother circuits of the liquid crystal display 600 are identical to thecircuits of the liquid crystal display 100, and for the sake of brevity,further discussion on the other circuits of liquid crystal display 600is omitted.

FIG. 7 is a circuit diagram schematically showing the structure of aliquid crystal display 700 in accordance with a fourth embodiment of thepresent invention. As shown in FIG. 7, the circuit structure of theliquid crystal display 700 is similar to the circuit structure of theliquid crystal display 400 shown in FIG. 4, differing only in that theplurality of parallel first common lines 131 and the plurality ofparallel second common lines 132 are replaced with a plurality ofparallel first common lines 135 and a plurality of parallel secondcommon lines 136. All the pluralities of first common lines 135 andsecond common lines 136 are perpendicular to the plurality of gate lines120. Each of the plurality of first common lines 135 receives a firstcommon voltage Vcom1, and each of the plurality of second common lines136 receives a second common voltage Vcom2. The first end of each firstliquid crystal capacitor 143 is coupled to a corresponding first commonline 135. The first end of each second liquid crystal capacitor 145 iscoupled to a corresponding second common line 136. The other circuits ofthe liquid crystal display 700 are identical to the circuits of theliquid crystal display 400, and for the sake of brevity, furtherdiscussion on the other circuits of liquid crystal display 700 isomitted.

To sum up, the liquid crystal display of the present invention is ableto operate with uniform feed-through voltage based on a design havingrequired gate-source capacitances of corresponding transistor switchesso as to eliminate the color-shift phenomenon. Furthermore, the liquidcrystal display of the present invention is also able to get rid of theflickering phenomenon through providing a common voltage changing inresponse to the feed-through voltage shift of the voltage drop betweenopposite sides of the liquid crystal layer. Moreover, because of theuniform feed-through voltage in the operation of the liquid crystaldisplay of the present invention, the reduction of available contrastrange for brightness control of each pixel of the liquid crystal displayof the present invention is not as serious as that of the prior-artliquid crystal display due to the minor reduction of available voltagerange of each pixel of the liquid crystal display of the presentinvention. In addition, as the capacitance ratio C_(D)/C_(B) of theliquid crystal display of the present invention is designed to have ahigher value, the color-shift phenomenon caused by deficient colorsaturation due to adjustment of different charging periods can becompensated by devising the corresponding transistor switches with thegate channel having a greater width/length ratio so as to achieve ahigher charging ratio of corresponding capacitors having brightcapacitance.

The present invention is by no means limited to the embodiments asdescribed above by referring to the accompanying drawings, which may bemodified and altered in a variety of different ways without departingfrom the scope of the present invention. Thus, it should be understoodby those skilled in the art that various modifications, combinations,sub-combinations and alternations might occur depending on designrequirements and other factors insofar as they are within the scope ofthe appended claims or the equivalents thereof.

1. A liquid crystal display comprising: a plurality of data lines, eachof the plurality of data lines being adapted to receive a correspondingdata signal; a plurality of gate lines crossed with the plurality ofdata lines perpendicularly, each of the plurality of gate lines beingadapted to receive a corresponding gate signal; a plurality of commonlines for receiving a common voltage; a plurality of storage units, eachof the plurality of storage units comprising: a first liquid crystalcapacitor comprising a first end coupled to a corresponding common lineof the plurality of common lines, and a second end; and a second liquidcrystal capacitor comprising a first end coupled to the correspondingcommon line of the plurality of common lines, and a second end; aplurality of first switches, each of the plurality of first switchescomprising: a first end coupled to the second end of a correspondingfirst liquid crystal capacitor of the plurality of first liquid crystalcapacitors; a second end coupled to a corresponding data line of theplurality of data lines; a gate coupled to a corresponding gate line ofthe plurality of gate lines, wherein the first switch controls a signalconnection between the first end and the second end of the first switchbased on a gate signal furnished to the gate of the first switch via thecorresponding gate line; and a first end capacitor coupled between thegate and the first end of the first switch; and a plurality of secondswitches, each of the plurality of second switches comprising: a firstend coupled to the second end of a corresponding second liquid crystalcapacitor of the plurality of second liquid crystal capacitors; a secondend coupled to the first end of a corresponding first switch of theplurality of first switches; a gate coupled to a corresponding gate lineof the plurality of gate lines, wherein the second switch controls asignal connection between the first end and the second end of the secondswitch based on a gate signal furnished to the gate of the second switchvia the corresponding gate line; and a first end capacitor coupledbetween the gate and the first end of the second switch; wherein acapacitance of the first end capacitor of the first switch is greaterthan a capacitance of the first end capacitor of the second switch. 2.The liquid crystal display of claim 1, wherein the capacitance of thefirst end capacitor of the first switch is devised according to thefollowing formula:${{\frac{{Cgs}\; 1}{C_{D} + C_{B} + {{Cgs}\; 1}} + \frac{{Cgs}\; 2}{C_{D} + {{Vgs}\; 2}}} = \frac{{Cgs}\; 1}{C_{B} + {{Cgs}\; 1}}};$where Cgs1 represents the capacitance of the first end capacitor of thefirst switch, Cgs2 represents the capacitance of the first end capacitorof the second switch, C_(B) represents a capacitance of the first liquidcrystal capacitor, and C_(D) represents a capacitance of the secondliquid crystal capacitor.
 3. The liquid crystal display of claim 1,wherein the first end capacitor of the first switch has a capacitor areawhich is greater than the capacitor area of the first end capacitor ofthe second switch.
 4. The liquid crystal display of claim 1, wherein thefirst end capacitor of the first switch comprises an insulation layer,the first end capacitor of the second switch comprises an insulationlayer, and a thickness of the insulation layer of the first endcapacitor of the first switch is less than a thickness of the insulationlayer of the first end capacitor of the second switch.
 5. The liquidcrystal display of claim 1, wherein the first end capacitor of the firstswitch comprises an insulation layer, the first end capacitor of thesecond switch comprises an insulation layer, and a dielectric constantof the insulation layer of the first end capacitor of the first switchis greater than a dielectric constant of the insulation layer of thefirst end capacitor of the second switch.
 6. The liquid crystal displayof claim 1, wherein the plurality of first switches and the plurality ofsecond switches comprise thin film transistors or MOS field effecttransistors.
 7. The liquid crystal display of claim 1, wherein theplurality of common lines are parallel or perpendicular to the pluralityof gate lines.
 8. A liquid crystal display comprising: a plurality ofdata lines, each of the plurality of data lines being adapted to receivea corresponding data signal; a plurality of gate lines crossed with theplurality of data lines perpendicularly, each of the plurality of gatelines being adapted to receive a corresponding gate signal; a pluralityof first common lines for receiving a first common voltage; a pluralityof second common lines for receiving a second common voltage; aplurality of storage units, each of the plurality of storage unitscomprising: a first liquid crystal capacitor comprising a first endcoupled to a corresponding first common line of the plurality of firstcommon lines, and a second end; and a second liquid crystal capacitorcomprising a first end coupled to a corresponding second common line ofthe plurality of second common lines, and a second end; a plurality offirst switches, each of the plurality of first switches comprising: afirst end coupled to the second end of a corresponding first liquidcrystal capacitor of the plurality of first liquid crystal capacitors; asecond end coupled to a corresponding data line of the plurality of datalines; a gate coupled to a corresponding gate line of the plurality ofgate lines, wherein the first switch controls a signal connectionbetween the first end and the second end of the first switch based on agate signal furnished to the gate of the first switch via thecorresponding gate line; and a first end capacitor coupled between thegate and the first end of the first switch; and a plurality of secondswitches, each of the plurality of second switches comprising: a firstend coupled to the second end of a corresponding second liquid crystalcapacitor of the plurality of second liquid crystal capacitors; a secondend coupled to the first end of a corresponding first switch of theplurality of first switches; a gate coupled to a corresponding gate lineof the plurality of gate lines, wherein the second switch controls asignal connection between the first end and the second end of the secondswitch based on a gate signal furnished to the gate of the second switchvia the corresponding gate line; and a first end capacitor coupledbetween the gate and the first end of the second switch; wherein acapacitance of the first end capacitor of the first switch is greaterthan a capacitance of the first end capacitor of the second switch. 9.The liquid crystal display of claim 8, wherein the plurality of firstcommon lines and the plurality of second common lines are substantiallyparallel or perpendicular to the plurality of gate lines.
 10. The liquidcrystal display of claim 8, wherein the capacitance of the first endcapacitor of the first switch is devised according to the followingformula:${{\frac{{Cgs}\; 1}{C_{D} + C_{B} + {{Cgs}\; 1}} + \frac{{Cgs}\; 2}{C_{D} + {{Vgs}\; 2}}} = \frac{{Cgs}\; 1}{C_{B} + {{Cgs}\; 1}}};$where Cgs1 represents the capacitance of the first end capacitor of thefirst switch, Cgs2 represents the capacitance of the first end capacitorof the second switch, C_(B) represents a capacitance of the first liquidcrystal capacitor, and C_(D) represents a capacitance of the secondliquid crystal capacitor.
 11. The liquid crystal display of claim 8,wherein the first end capacitor of the first switch has a capacitor areawhich is greater than the capacitor area of the first end capacitor ofthe second switch.
 12. The liquid crystal display of claim 8, whereinthe first end capacitor of the first switch comprises an insulationlayer, the first end capacitor of the second switch comprises aninsulation layer, and a thickness of the insulation layer of the firstend capacitor of the first switch is less than a thickness of theinsulation layer of the first end capacitor of the second switch. 13.The liquid crystal display of claim 8, wherein the first end capacitorof the first switch comprises an insulation layer, the first endcapacitor of the second switch comprises an insulation layer, and adielectric constant of the insulation layer of the first end capacitorof the first switch is greater than a dielectric constant of theinsulation layer of the first end capacitor of the second switch. 14.The liquid crystal display of claim 8, wherein the plurality of firstswitches and the plurality of second switches comprise thin filmtransistors or MOS field effect transistors.
 15. A liquid crystaldisplay comprising: a plurality of data lines, each of the plurality ofdata lines being adapted to receive a corresponding data signal; aplurality of gate lines crossed with the plurality of data linesperpendicularly, each of the plurality of gate lines being adapted toreceive a corresponding gate signal; a plurality of common lines forreceiving a common voltage, the plurality of parallel common lines beingsubstantially parallel or perpendicular to the plurality of gate lines;a plurality of storage units, each of the plurality of storage unitscomprising: a first liquid crystal capacitor comprising a first endcoupled to a corresponding common line of the plurality of common lines,and a second end; and a second liquid crystal capacitor comprising afirst end coupled to the corresponding common line of the plurality ofcommon lines, and a second end; a plurality of first switches, each ofthe plurality of first switches comprising: a first end coupled to thesecond end of a corresponding first liquid crystal capacitor of theplurality of first liquid crystal capacitors; a second end coupled to acorresponding data line of the plurality of data lines; a gate channelcoupled between the first end and the second end of the firsttransistor; and a gate coupled to a corresponding gate line of theplurality of gate lines, wherein the first switch controls a signalconnection between the first end and the second end of the first switchbased on a gate signal furnished to the gate of the first switch via thecorresponding gate line; and a plurality of second switches, each of theplurality of second switches comprising: a first end coupled to thesecond end of a corresponding second liquid crystal capacitor of theplurality of second liquid crystal capacitors; a second end coupled tothe first end of a corresponding first switch of the plurality of firstswitches; a gate channel coupled between the first end and the secondend of the second transistor; and a gate coupled to a corresponding gateline of the plurality of gate lines, wherein the second switch controlsa signal connection between the first end and the second end of thesecond switch based on a gate signal furnished to the gate of the secondswitch via the corresponding gate line; wherein a ratio of width tolength of the gate channel of the first switch is greater than a ratioof width to length of the gate channel of the second switch.
 16. Theliquid crystal display of claim 15, wherein the first switch furthercomprises a first end capacitor coupled between the gate and the firstend of the first switch; and the second switch further comprises a firstend capacitor coupled between the gate and the first end of the secondswitch; wherein a capacitance of the first end capacitor of the firstswitch is greater than a capacitance of the first end capacitor of thesecond switch.
 17. The liquid crystal display of claim 16, wherein thecapacitance of the first end capacitor of the first switch is devisedaccording to the following formula:${{\frac{{Cgs}\; 1}{C_{D} + C_{B} + {{Cgs}\; 1}} + \frac{{Cgs}\; 2}{C_{D} + {{Vgs}\; 2}}} = \frac{{Cgs}\; 1}{C_{B} + {{Cgs}\; 1}}};$where Cgs1 represents the capacitance of the first end capacitor of thefirst switch, Cgs2 represents the capacitance of the first end capacitorof the second switch, C_(B) represents a capacitance of the first liquidcrystal capacitor, and C_(D) represents a capacitance of the secondliquid crystal capacitor.
 18. The liquid crystal display of claim 16,wherein the first end capacitor of the first switch has a capacitor areawhich is greater than the capacitor area of the first end capacitor ofthe second switch.
 19. The liquid crystal display of claim 16, whereinthe first end capacitor of the first switch comprises an insulationlayer, the first end capacitor of the second switch comprises aninsulation layer; a thickness of the insulation layer of the first endcapacitor of the first switch is less than a thickness of the insulationlayer of the first end capacitor of the second switch; and a dielectricconstant of the insulation layer of the first end capacitor of the firstswitch is greater than a dielectric constant of the insulation layer ofthe first end capacitor of the second switch.
 20. A liquid crystaldisplay comprising: a plurality of data lines, each of the plurality ofdata lines being adapted to receive a corresponding data signal; aplurality of gate lines crossed with the plurality of data linesperpendicularly, each of the plurality of gate lines being adapted toreceive a corresponding gate signal; a plurality of first common linesfor receiving a first common voltage; a plurality of second common linesfor receiving a second common voltage; a plurality of storage units,each of the plurality of storage units comprising: a first liquidcrystal capacitor comprising a first end coupled to a correspondingfirst common line of the plurality of first common lines, and a secondend; and a second liquid crystal capacitor comprising a first endcoupled to a corresponding second common line of the plurality of secondcommon lines, and a second end; a plurality of first switches, each ofthe plurality of first switches comprising: a first end coupled to thesecond end of a corresponding first liquid crystal capacitor of theplurality of first liquid crystal capacitors; a second end coupled to acorresponding data line of the plurality of data lines; a gate channelcoupled between the first end and the second end of the firsttransistor; and a gate coupled to a corresponding gate line of theplurality of gate lines, wherein the first switch controls a signalconnection between the first end and the second end of the first switchbased on a gate signal furnished to the gate of the first switch via thecorresponding gate line; and a plurality of second switches, each of theplurality of second switches comprising: a first end coupled to thesecond end of a corresponding second liquid crystal capacitor of theplurality of second liquid crystal capacitors; a second end coupled tothe first end of a corresponding first switch of the plurality of firstswitches; a gate channel coupled between the first end and the secondend of the second transistor; and a gate coupled to a corresponding gateline of the plurality of gate lines, wherein the second switch controlsa signal connection between the first end and the second end of thesecond switch based on a gate signal furnished to the gate of the secondswitch via the corresponding gate line; wherein a ratio of width tolength of the gate channel of the first switch is greater than a ratioof width to length of the gate channel of the second switch.
 21. Theliquid crystal display of claim 20, wherein the first switch furthercomprises a first end capacitor coupled between the gate and the firstend of the first switch; and the second switch further comprises a firstend capacitor coupled between the gate and the first end of the secondswitch; wherein a capacitance of the first end capacitor of the firstswitch is greater than a capacitance of the first end capacitor of thesecond switch.
 22. The liquid crystal display of claim 21, wherein thecapacitance of the first end capacitor of the first switch is devisedaccording to the following formula:${{\frac{{Cgs}\; 1}{C_{D} + C_{B} + {{Cgs}\; 1}} + \frac{{Cgs}\; 2}{C_{D} + {{Vgs}\; 2}}} = \frac{{Cgs}\; 1}{C_{B} + {{Cgs}\; 1}}};$where Cgs1 represents the capacitance of the first end capacitor of thefirst switch, Cgs2 represents the capacitance of the first end capacitorof the second switch, C_(B) represents a capacitance of the first liquidcrystal capacitor, and C_(D) represents a capacitance of the secondliquid crystal capacitor.
 23. The liquid crystal display of claim 21,wherein the first end capacitor of the first switch has a capacitor areawhich is greater than the capacitor area of the first end capacitor ofthe second switch.
 24. The liquid crystal display of claim 21, whereinthe first end capacitor of the first switch comprises an insulationlayer, the first end capacitor of the second switch comprises aninsulation layer; a thickness of the insulation layer of the first endcapacitor of the first switch is less than a thickness of the insulationlayer of the first end capacitor of the second switch; and a dielectricconstant of the insulation layer of the first end capacitor of the firstswitch is greater than a dielectric constant of the insulation layer ofthe first end capacitor of the second switch.